8.3.63
प्राक्सितादड्व्यवायेऽपि
Operational rule vidhi
(The substitution of ष् for स् to be taught hereafter, will take place) for all roots up to सित् exclusive in परिनिविभ्यः सेवसितसयसिवुसहसुट्स्तुस्वञ्जाम् (8.3.70), even when the augment अट् intervenes (between the स and the efficient letter).
Word by word (padaccheda)
Indeclinable प्राक् avyayaLeft context सितात् pañcamī · ekavacanaRight context अड्व्यवाये saptamī · ekavacanaIndeclinable अपि avyaya
- Indeclinable An avyaya such as च "and", वा "optionally", न "not".
- Left context Pañcamī (5th case): "after X", the operation applies to what follows (1.1.67 तस्मादित्युत्तरस्य). Also used for limits and sources.
- Right context Saptamī (7th case): "when X follows", the operation applies to what precedes (1.1.66 तस्मिन्निति निर्दिष्टे पूर्वस्य). Also a condition or domain ("in the sense of").
Full reading
प्राक् सितात् अड्व्यवाये अपि
Pāṇini leaves out words that carry over from earlier sūtras. Expand to see the rule as a reader actually understands it.
Commentary
(The substitution of ष् for स् to be taught hereafter, will take place) for all roots up to सित् exclusive in परिनिविभ्यः सेवसितसयसिवुसहसुट्स्तुस्वञ्जाम् 8.3.70, even when the augment अट् intervenes (between the स and the efficient letter).
The root सित् occurs in sutra 8.3.70. Thus 8.3.65 teaches ष change: as अभिषुणोति, परिषुणोति, विषुणोति, निषुणोति ॥ So also when अट् intervenes; as अभ्यषुणोत्, पर्यषुणोत्, व्यषुणोत्, न्यषुणोत् ॥ The force of अपि is that the change takes place even when the augment अट् does not come, i. e. in cases other than the augment.
Śrīśa Chandra Vasu, The Ashtadhyayi of Panini (1897), via ashtadhyayi.com.